少有人走的路勇哥来测试一下全部的查询运算符。
每天测试一部分，代码会持续更新中……
using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace ConsoleApp1
{
class Person
{
public string Name { set; get; }
public int Age { set; get; }
public override string ToString()
{
return $"{Name},{Age}";
}
}
class Department
{
public string Name { set; get; }
public Person Employee { set; get; }
public override string ToString()
{
return $"{Name}";
}
}
class Program
{
private static List<Racer> racers;
public static IList<Racer> GetChampions()
{
if (racers == null)
{
racers = new List<Racer>(40);
racers.Add(new Racer("Nino", "Farina", "Italy", 33, 5, new int[] { 1950 }, new string[] { "Alfa Romeo" }));
racers.Add(new Racer("Alberto", "Ascari", "Italy", 32, 10, new int[] { 1952, 1953 }, new string[] { "Ferrari" }));
racers.Add(new Racer("Juan Manuel", "Fangio", "Argentina", 51, 24, new int[] { 1951, 1954, 1955, 1956, 1957 }, new string[] { "Alfa Romeo", "Maserati", "Mercedes", "Ferrari" }));
racers.Add(new Racer("Mike", "Hawthorn", "UK", 45, 3, new int[] { 1958 }, new string[] { "Ferrari" }));
racers.Add(new Racer("Phil", "Hill", "USA", 48, 3, new int[] { 1961 }, new string[] { "Ferrari" }));
racers.Add(new Racer("John", "Surtees", "UK", 111, 6, new int[] { 1964 }, new string[] { "Ferrari" }));
racers.Add(new Racer("Jim", "Clark", "UK", 72, 25, new int[] { 1963, 1965 }, new string[] { "Lotus" }));
racers.Add(new Racer("Jack", "Brabham", "Australia", 125, 14, new int[] { 1959, 1960, 1966 }, new string[] { "Cooper", "Brabham" }));
racers.Add(new Racer("Denny", "Hulme", "New Zealand", 112, 8, new int[] { 1967 }, new string[] { "Brabham" }));
racers.Add(new Racer("Graham", "Hill", "UK", 176, 14, new int[] { 1962, 1968 }, new string[] { "BRM", "Lotus" }));
racers.Add(new Racer("Jochen", "Rindt", "Austria", 60, 6, new int[] { 1970 }, new string[] { "Lotus" }));
racers.Add(new Racer("Jackie", "Stewart", "UK", 99, 27, new int[] { 1969, 1971, 1973 }, new string[] { "Matra", "Tyrrell" }));
racers.Add(new Racer("Emerson", "Fittipaldi", "Brazil", 143, 14, new int[] { 1972, 1974 }, new string[] { "Lotus", "McLaren" }));
racers.Add(new Racer("James", "Hunt", "UK", 91, 10, new int[] { 1976 }, new string[] { "McLaren" }));
racers.Add(new Racer("Mario", "Andretti", "USA", 128, 12, new int[] { 1978 }, new string[] { "Lotus" }));
racers.Add(new Racer("Jody", "Scheckter", "South Africa", 112, 10, new int[] { 1979 }, new string[] { "Ferrari" }));
racers.Add(new Racer("Alan", "Jones", "Australia", 115, 12, new int[] { 1980 }, new string[] { "Williams" }));
racers.Add(new Racer("Keke", "Rosberg", "Finland", 114, 5, new int[] { 1982 }, new string[] { "Williams" }));
racers.Add(new Racer("Niki", "Lauda", "Austria", 173, 25, new int[] { 1975, 1977, 1984 }, new string[] { "Ferrari", "McLaren" }));
racers.Add(new Racer("Nelson", "Piquet", "Brazil", 204, 23, new int[] { 1981, 1983, 1987 }, new string[] { "Brabham", "Williams" }));
racers.Add(new Racer("Ayrton", "Senna", "Brazil", 161, 41, new int[] { 1988, 1990, 1991 }, new string[] { "McLaren" }));
racers.Add(new Racer("Nigel", "Mansell", "UK", 187, 31, new int[] { 1992 }, new string[] { "Williams" }));
racers.Add(new Racer("Alain", "Prost", "France", 197, 51, new int[] { 1985, 1986, 1989, 1993 }, new string[] { "McLaren", "Williams" }));
racers.Add(new Racer("Damon", "Hill", "UK", 114, 22, new int[] { 1996 }, new string[] { "Williams" }));
racers.Add(new Racer("Jacques", "Villeneuve", "Canada", 165, 11, new int[] { 1997 }, new string[] { "Williams" }));
racers.Add(new Racer("Mika", "Hakkinen", "Finland", 160, 20, new int[] { 1998, 1999 }, new string[] { "McLaren" }));
racers.Add(new Racer("Michael", "Schumacher", "Germany", 287, 91, new int[] { 1994, 1995, 2000, 2001, 2002, 2003, 2004 }, new string[] { "Benetton", "Ferrari" }));
racers.Add(new Racer("Fernando", "Alonso", "Spain", 177, 27, new int[] { 2005, 2006 }, new string[] { "Renault" }));
racers.Add(new Racer("Kimi", "Räikkönen", "Finland", 148, 17, new int[] { 2007 }, new string[] { "Ferrari" }));
racers.Add(new Racer("Lewis", "Hamilton", "UK", 90, 17, new int[] { 2008 }, new string[] { "McLaren" }));
racers.Add(new Racer("Jenson", "Button", "UK", 208, 12, new int[] { 2009 }, new string[] { "Brawn GP" }));
racers.Add(new Racer("Sebastian", "Vettel", "Germany", 81, 21, new int[] { 2010, 2011 }, new string[] { "Red Bull Racing" }));
}
return racers;
}
public struct Employee
{
/// <summary>
/// 名字
/// </summary>
public string Name;
/// <summary>
/// 年纪
/// </summary>
public int Age;
/// <summary>
/// 性别
/// </summary>
public string Gender;
/// <summary>
/// 薪水
/// </summary>
public int Salary;
}
public struct Employee2
{
/// <summary>
/// 名字
/// </summary>
public string Name;
/// <summary>
/// 语言
/// </summary>
public string language;
/// <summary>
/// 城市
/// </summary>
public string city;
/// <summary>
/// 已婚
/// </summary>
public bool married;
}
public static List<Employee> employees = new List<Employee>()
{
new Employee(){ Age=40, Name="Peter Claus", Gender="Male", Salary=61000},
new Employee(){ Age=35, Name="Jose Mond", Gender="Male", Salary=62000},
new Employee(){ Age=38, Name="Helen Gant", Gender="Female", Salary=38000},
new Employee(){ Age=42, Name="Jo Parker", Gender="Male", Salary=52000},
new Employee(){ Age=22, Name="Alex Mueller", Gender="Male", Salary=39000},
new Employee(){ Age=53, Name="Abbi Black", Gender="female", Salary=56000},
new Employee(){ Age=51, Name="Mike Mockson", Gender="Male", Salary=82000}
};
public static List<Employee2> employees2 = new List<Employee2>()
{
new Employee2(){ Name="Peter Claus", city="wu han", language="Chinese", married=false},
new Employee2(){ Name="Jose Mond", city="wu han", language="English", married=false},
new Employee2(){ Name="Helen Gant", city="chong qing", language="Chinese", married=false},
new Employee2(){ Name="Jo Parker", city="bei jing", language="Chinese", married=true},
new Employee2(){ Name="Alex Mueller", city="he fei", language="Chinese", married=false},
new Employee2(){ Name="Abbi Black", city="chong qing", language="Chinese", married=true},
new Employee2(){ Name="Mike Mockson", city="dong guang", language="English", married=true},
};
static Person p1 = new Person() { Name = "ABC", Age = 18 };
static Person p2 = new Person() { Name = "EFG", Age = 19 };
static Person p3 = new Person() { Name = "LMN", Age = 20 };
static Person p4 = new Person() { Name = "XYZ", Age = 21 };
static List<Person> pList = new List<Person> { p1, p2, p3, p4 };
static Department d1 = new Department() { Name = "A1", Employee = p1 };
static Department d2 = new Department() { Name = "A2", Employee = p2 };
static Department d3 = new Department() { Name = "A3", Employee = p1 };
static Department d4 = new Department() { Name = "B1", Employee = p3 };
static Department d5 = new Department() { Name = "B2", Employee = p4 };
static Department d6 = new Department() { Name = "B3", Employee = p4 };
static List<Department> dList = new List<Department> { d1, d2, d3, d4, d5, d6 };
public static ArrayList arylist = new ArrayList() { "Mango", "Orange", "Apple",32,
new Employee(){ Age=46, Name="Peter blaus", Gender="Male", Salary=66000},
"Banana" };
static void printf<T>(IEnumerable<T> data, string msg="")
{
var sb1 = new StringBuilder();
if (data is IEnumerable<Employee>)
{
((IEnumerable<Employee>)data).ToList().ForEach(s => sb1.Append($"{s.Age},{s.Name},{s.Gender},{s.Salary}\r\n"));
}
else if(data is IEnumerable<int> || data is IEnumerable<string>)
{
data.ToList().ForEach(s => sb1.Append(s.ToString() + "\r\n"));
}
else
{
foreach(var m in data)
{
sb1.Append(m.ToString()+"\r\n");
}
}
if(msg.Length>0)
{
Console.WriteLine($"{msg}----------------------------------");
}
Console.WriteLine(sb1.ToString());
}
static void Main(string[] args)
{
//过滤
printf(employees.Where((s) => s.Salary >= 52000), "过滤");
printf(arylist.OfType<int>());
//投影
printf(employees
.Where(s => s.Name.StartsWith("J"))
.Select(s => s), "投影");
//返回单列
printf(employees
.Where(s => s.Name.StartsWith("J"))
.Select(s => s.Name)
.ToList());
//多列的匿名类
printf(employees
.Where(s => s.Name.StartsWith("J"))
.Select(s =>new { s.Name,s.Age,s.Salary })
);
//分区
//Skip:跳过序列中的指定位置之前的元素。
printf(employees.Skip(4), "分区");
//SkipWhile:基于谓词函数跳过元素，直到某元素不再满足条件。
printf(employees.SkipWhile(s => s.Age < 50));
//Take:提取序列中的指定位置之前的元素。
printf(employees.Take(2));
//TakeWhile:基于谓词函数提取元素，直到某元素不再满足条件。
printf(employees.TakeWhile(s => s.Age <50));
//连接
//Join:根据键选择器函数联接两个序列并提取值对。
printf(employees.Join(employees2, s => s.Name, s2 => s2.Name,
(s, s2) => new
{
Name = s.Name,
Age = s.Age,
Gender = s.Gender,
Salary = s.Salary,
City = s2.city,
Language = s2.language,
Married = s2.married
}), "分区");
//GroupJoin: 根据键选择器函数联接两个序列，并对每个元素的结果匹配项进行分组。
var result2 = pList.Join(dList,
person => person,
department => department.Employee,
(person, department) => new
{
Person = person,
Department = department
});
foreach (var item1 in result2)
{
Console.Write($"Name:{item1.Person} & Department:{item1.Department} ");
Console.WriteLine();
}
Console.WriteLine();
var result= pList.GroupJoin(dList,
person => person,
department => department.Employee,
(person, departments) => new
{
Person = person,
Department = departments.Select(d => d)
});
foreach (var item1 in result)
{
Console.Write($"Name:{item1.Person} & ");
foreach (var item22 in item1.Department)
{
if (item1.Department.First() == item22)
Console.Write($"Department:{item22} ");
else
Console.Write($"{item22} ");
}
Console.WriteLine();
}
//串联
//排序
//分组
//集合
//转换
//等同
//元素
//生成
//数量
//聚集
//1、where子句
var racers = from r in GetChampions()
where r.Wins > 15 && (r.Country == "Brazil" || r.Country == "Austria")
select r;
var item = GetChampions().Where(p => p.Wins > 15 && (p.Country == "Brazil" || p.Country == "Austria")).Select(r => r);
//2、根据索引筛选
var racers1 = GetChampions().
Where((r, index) => r.LastName.StartsWith("A") && index % 2 != 0);
//3、类型筛选
object[] data = { "one", 2, 3, "four", "five", 6 };
var query = data.OfType<string>();
//4、复合的from子句
var ferrariDrivers = from r in GetChampions()
from c in r.Cars
where c == "Ferrari"
orderby r.LastName
select r.FirstName + " " + r.LastName;
var item2 = GetChampions().SelectMany(r => r.Cars, (r, c) => new { Racer = r, Car = c }).
Where(r => r.Car == "Ferrari").OrderBy(r => r.Racer.LastName).Select(r => r.Racer.FirstName + "" + r.Racer.LastName);
//5、排序
var racers3 = from r in GetChampions()
where r.Country == "Brazil"
orderby r.Wins descending
select r;
var racers2 = from r in GetChampions()
orderby r.Country, r.LastName, r.FirstName
select r;
var racers4 = GetChampions().OrderBy(r => r.Country).ThenBy(r => r.LastName).ThenBy(r => r.FirstName);
//6、分组
var countries = from r in GetChampions()
group r by r.Country into g
orderby g.Count() descending, g.Key
where g.Count() >= 2
select new { Country = g.Key, Count = g.Count() };
var item5 = GetChampions().GroupBy(r => r.Country).OrderByDescending(p => p.Count()).
ThenBy(p => p.Key).Where(p => p.Count() >= 2).Select(p => new { Country = p.Key, Count = p.Count() });
//7、内链接
var racers7 = from r in GetChampions()
from y in r.Years
select new
{
Year = y,
Name = r.FirstName + " " + r.LastName
};
//var teams7 = from t in GetContructorChampions()
// from y in t.Years
// select new
// {
// Year = y,
// Name = t.Name
// };
//8、左连接
//var racersAndTeams =
// (from r in racers
// join t in teams on r.Year equals t.Year into rt
// from t in rt.DefaultIfEmpty()
// orderby r.Year
// select new
// {
// Year = r.Year,
// Champion = r.Name,
// Constructor = t == null ? "no constructor championship" : t.Name
// }).Take(10);
//9、zip 合并
var racerNames = from r in GetChampions()
where r.Country == "Italy"
orderby r.Wins descending
select new
{
Name = r.FirstName + " " + r.LastName
};
var racerNamesAndStarts = from r in GetChampions()
where r.Country == "Italy"
orderby r.Wins descending
select new
{
LastName = r.LastName,
Starts = r.Starts
};
var racers9 = racerNames.Zip(racerNamesAndStarts, (first, second) => first.Name + ", starts: " + second.Starts);
//10、聚合函数
var query10 = from r in GetChampions()
let numberYears = r.Years.Count()
where numberYears >= 3
orderby numberYears descending, r.LastName
select new
{
Name = r.FirstName + " " + r.LastName,
TimesChampion = numberYears
};
var countries10 = (from c in
from r in GetChampions()
group r by r.Country into c
select new
{
Country = c.Key,
Wins = (from r1 in c
select r1.Wins).Sum()
}
orderby c.Wins descending, c.Country
select c).Take(5);
//https://www.cnblogs.com/farmer-y/p/5977483.html
Console.ReadLine();
}
}
public class Racer : IComparable<Racer>, IFormattable
{
public Racer()
{ }
public Racer(string firstName, string lastName, string country, int starts, int wins)
: this(firstName, lastName, country, starts, wins, null, null)
{
}
public Racer(string firstName, string lastName, string country, int starts, int wins, IEnumerable<int> years, IEnumerable<string> cars)
{
this.FirstName = firstName;
this.LastName = lastName;
this.Country = country;
this.Starts = starts;
this.Wins = wins;
this.Years = new List<int>(years);
this.Cars = new List<string>(cars);
}
public string FirstName { get; set; }
public string LastName { get; set; }
public string Country { get; set; }
public int Wins { get; set; }
public int Starts { get; set; }
public IEnumerable<string> Cars { get; private set; }
public IEnumerable<int> Years { get; private set; }
public override string ToString()
{
return String.Format("{0} {1}", FirstName, LastName);
}
public int CompareTo(Racer other)
{
if (other == null) return -1;
return string.Compare(this.LastName, other.LastName);
}
public string ToString(string format)
{
return ToString(format, null);
}
public string ToString(string format,
IFormatProvider formatProvider)
{
switch (format)
{
case null:
case "N":
return ToString();
case "F":
return FirstName;
case "L":
return LastName;
case "C":
return Country;
case "S":
return Starts.ToString();
case "W":
return Wins.ToString();
case "A":
return String.Format("{0} {1}, {2}; starts: {3}, wins: {4}",
FirstName, LastName, Country, Starts, Wins);
default:
throw new FormatException(String.Format("Format {0} not supported", format));
}
}
}
}参考资料：
C#中使用Join与GroupJoin将两个集合进行关联与分组 https://www.cnblogs.com/newcapecjmc/p/11193852.html
LINQ 标准查询操作概述 https://www.cnblogs.com/liqingwen/p/5801249.html
---------------------
作者：hackpig
来源：www.skcircle.com
版权声明：本文为博主原创文章，转载请附上博文链接！
本文出自勇哥的网站《少有人走的路》wwww.skcircle.com，转载请注明出处！讨论可扫码加群：
